Piezoelectric switch

Abstract

A piezoelectric switch includes a piezoelectric element which is electrically connected to a printed circuit board by a pair of wires. A unitary plastic carrier is designed to retain both the piezoelectric element and the printed circuit board fixedly mounted thereon. In turn, the plastic carrier is sized and shaped to be co-axially disposed within the interior cavity of a generally cylindrically-shaped protective housing, wherein the plastic carrier is provided with at least one flexible finger which is configured to snap-fit into engagement within an annular groove formed in the inner surface of the housing so as to retain the carrier in place within the interior cavity. With the carrier fixed in place within the housing, an adhesive spacer disposes the piezoelectric element in contact with the inner surface of a touch plate provided in the housing. Accordingly, in use, the application of a tactile input onto the outer surface of the touch plate in turn causes the approximate center of the piezoelectric element to slightly deform. In response thereto, the piezoelectric element generates an output signal which passes to the printed circuit board. Based on the output signal received, the printed circuit board regulates the state of the piezoelectric switch.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates generally to electrical switches and more particularly to piezoelectric switches.[0002]Piezoelectric switches, also commonly referred to simply as piezo switches, are well known and widely used in the electrical switch industry.[0003]A piezoelectric switch traditionally includes a piezoelectric element comprising a disc-shaped piezoelectric plate and a disc-shaped conductive plate that are affixed together by an adhesive. The piezoelectric plate is commonly constructed out of piezo crystal and serves as the positive terminal for the switch. The conductive plate is typically constructed out of a conductive metal, such as brass, and serves as the negative terminal for the switch. Each of the above-described plates of the piezoelectric element is electrically connected to a printed circuit board which in turn supports the output prongs (i.e., conductive terminals) for the switch.[0004]The piezoelectric element and printed c...

AI Technical Summary

Benefits of technology

[0013]It is still another object of this invention to provide a piezoelectric switch of the type as described above in which the piezoelectric element is mounted within the protective housing in such a manner so as to optimize the success rate of the switch.

[0014]It is yet still another object of this invention to provide a piezoelectric switch of the type as described above which includes a minimum number of parts, which is inexpensive to manufacture and which is easy to use.

Problems solved by technology

Although well known and widely used in commerce, piezoelectric switches of the type as described above have been found to suffer from a notable drawback.

Specifically, it has been found that the use of double-sided tape to affix the piezoelectric element to the inner surface of the touch plate can compromise the success rate of the switch in use.

However, because the entire surface of the piezo crystal is evenly affixed to the inner surface of the contact plate by an adhesive (which may, in turn, weaken over time), the application of an input force onto the housing is just as likely to cause the outer periphery of the piezo crystal to deform as it is to cause the approximate center of the piezo crystal to deform, which is highly undesirable.

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